Exam Question

### (a) Importance of Measuring Bearing Clearance in a Diesel Engine
Measuring bearing clearance is a critical diagnostic and preventative maintenance task for ensuring the reliability and safety of a marine diesel engine. The primary reasons for its importance are:
1. **Maintenance of Hydrodynamic Lubrication:** The specified clearance is precisely designed to allow the formation of a wedge-shaped, high-pressure oil film between the rotating journal and the stationary bearing shell. This hydrodynamic film supports the load, prevents metal-to-metal contact, and minimizes friction and wear.
* **Insufficient Clearance:** If the clearance is too small, the oil film cannot form properly. This leads to boundary lubrication, increased friction, overheating, wiping of the bearing material (white metal), and eventual seizure of the bearing.